Contemporaneous

Look in other contemporaneous works to see whether that idea was common then.

Source: wiktionary

Let AE and ae be two Lines indefinitely extended each way, along which two moving Things or Points may paſs from afar, and at the ſame time may reach the places A and a, B and b, C and c, D and d, &c. and let B be the Point, by its diſtance from which, the Motion of the moving thing or point in AE is eſtimated; so that — BA, BC, BD, BE, ſucceſſively, may be the flowing Quantities, when the moving thing is in the places A, C, D, E. Likewiſe let b be a like point in the other Line. Then will — BA and — ba be contemporaneous Fluents, as alſo BC and bc, BD and bd, BE and be, &c. […] [T]he contemporaneous parts AB and ab, BC and bc, CD and cd, DE and de are of the ſame length in both caſes. And thus in Equations in which theſe Quantities are repreſented, the contemporaneous parts of Quantities are not therefore changed, notwithſtanding their abſolute magnitude may be increaſed or diminiſhed by ſome given Quantity.

Source: wiktionary

In ancient times, as was formerly remarked, every event that excited any degree of interest, was wrought up in verse by the poets, and transmitted, by the aid of memory, from one generation to another. Other circumstances of a public nature, which gave less scope to the imagination, or could scarcely admit of amplification, were engraven on brass or marble, or stamped upon medals. In these different ways the memory of some ancient occurrences was imperfectly preserved, and afforded the means and materials, when writing came into use, to secure contemporaneous events from perishing for ever, and of making them more generally known.

Source: wiktionary

You know that Meroïtic is an ancient Nubian writing system of the third, or fourth century B.C., and is a script which conceals a typically African language. […] [I]f this script is deciphered, we will have in that respect the testimony of an African language which goes back 2,400 years, that is to say [back to a period] fairly contemporaneous with Latin and other languages of antiquity.

Source: wiktionary